Can you overfeed a combination fed baby?

Hi guys, FTM here, and have had to combination feed since birth due to milk coming in late and baby being dehydrated and losing weight. I'm confused about cluster feeding with formula. Basically, I still don't think I'm a big milk producer; pumping only seems to yield about 30ml max. I never count the times he's on the breast because I have no idea how much he's getting, and I doubt it's loads. He's 13 weeks old and I think having a growth spurt; he seems to be constantly hungry. The NHS website says that formula fed babies can cluster feed, but to be careful not to overfeed them. How does that work? I try to track that he's not getting more than the recommended amount of formula each day, but if he's constantly crying for food, how do I not overfeed? Help, please?